Device for lubricating two-stroke cycle internal combustion engines using light fuel



4, 1965 w. STAEGE ETAL 3,202,102

DEVICE FOR LUBRICATING TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINESUSING LIGHT FUEL Filed Nov. 6, 1961 2 Sheets-Sheet 1 Fig. I

Fig.2

4, 1965 w. STAEGE ETAL 3,202,102

DEVICE FOR LUBRICATING TWO-STROKE CYCLE INTERNAL COMBUSTION ENGINESUSING LIGHT FUEL Filed Nov. 6, 1961 2 Sheets-Sheet 2 Fig.3

United States Patent DEVICE FOR LUBRICATING TWO-STROKE CYCLE INTERNALCOWUSTION ENGINES USING LIGHT FUEL Werner Staege and Rudolf Schenk,Munich, Germany, assignors to Kugelfischer Georg Schafer & Co.,Schweinfurt, Germany Filed Nov. 6, 1961, Scr. No. 152,120 Claimspriority, application Germany, Nov. 12, 1960, K 42,143 9 Claims. (Cl.103-7) This invention relates to a method of lubricating an internalcombustion engine operating on the two-stroke cycle system and usinglight fuel whereby a pressurized lubricant is supplied to the engine bymeans of a separate lubricating oil pump which is independent of thefuel supply system. The invention also concerns a lubricating oil pumpadapted to carry the method of the invention into practice. The saidmethod which has been known as ,fresh oil lubrication affords animportant advantage over the so-called mixture lubricating system inwhich a predetermined proportion of lubricating oil is admixed with thelight fuel. This lubricating oil forms a con-v stituent of the fuel/ airmixture prepared in the carburettor and is carried, by the fuel/airmixture, to the various points to be-lubricated. The advantage residesin the fact that the internal combustion engine may be fitted with twoseparate tanks, namely a fuel tank and an oil tank. Moreover, it ispossible to control the supply of lubricating oilto the engine by meansof the rate-ofdelivery control member of the oil pump so as to match theoil supply with the operating conditions of the internal combustionengine independently of the fuel supply. On the other hand, however, itis an inherent drawback of the fresh oil lubricating system that incases in which the internal combustion engine is operated underconditions of low ambient temperatures'the lubricating oil is no longerelfectively distributed because the oil tends to become lessfree-flowing at lower temperatures, it being even possible that thetemperature of the oil drops below the point of congelation, this inturn causing undesirable wear and, under certain conditions, seriousdamage to the engine.

In order to provide for'the afore-described advantageous fresh oillubricating method to be rendered usable even under conditions of verylow ambient temperatures, the present invention provides for lubricatingoil and light fuel serving to dilute the oil to be brought into contactin the lubricating oil pump which then serves to supply the engine witha mixture of lubricating oil and light fuel. Thus, according to theinvention, a mixture of lubricating oil and light fuel is prepared, theformation of this mixture, in contrast to the known mixture lubricatingsystern, occurring independently of the formation of the fuel/ airmixture with which the engine is supplied, with the oil/fuel mixturebeing exclusively prepared in the lubrieating oil supply means.

According to another aspect of the invention, the lubrieating oil pumpmay be adapted alternatingly to deliver lubricating oil .and light fuel,the formation of the oil/fuel mixture being effected by the deliverypressure in the de livery line leading from the pressure chamber of theoil pump to the internal combustion engine. During operation of theengine, this arrangement ensures the supply of a constant oil/fuelmixture, the mixture ratio being a function of the adjustment of thelubricating oil pump.

*For the purpose of carrying the method of the invention into effectthere is provided a lubricating oil pump in the form of a valvelessplunger type pump having a pump plunger adapted to be reciprocated andsimultaneously rotated. The pump plunger having at least one controlmeans provided therein which control means serve, before each pressurestroke, to connect, according to the selected mixture ratio, thepressure chamber of the pump with suitable supply ports for lubricatingoil and for light fuel. The arrangement is such that during the pressurestroke of the plunger the media acted upon by the plunger aretransferred into a mixing chamber disposed upstream of the deliveryconnection of the pump. According to still wherein FIG. 1 is a verticalcross section of a lubricating oil pump according to the invention;

FIG. 2 is a plan view of the pump of FIG. 1;

FIG. 3 is a vertical cross section along the line III-III of FIG. 1; and

FIG. 4 is a transverse cross section along the line IV- [W of FIG. 1.

The embodiment of a pump shown in the drawings includes a pump plunger 1which is adapted to be simultaneously reciprocated and rotated, with theplunger being driven in rotation by a pump drive shaft 2 extendingperpendicularly to the plunger axis, and having formed therein a drivewarm 3 meshing with a worm gear 4 rigidly connected to the plunger. Theupward stroke motion of plunger 1 is effected against the action of areturn spring 5 in the form of a compression spring by a cam face 6provided on the under side of worm gear 4 and co-operating with a stopor abutment 7 mounted in the pump body. The cam face 6, in the case ofthe embodiment shown, is designed in such a manner that the plungerperforms two delivery strokes per revolution. The upper end of theplunger 1 is provided with an axial groove 9 opening towards thepressure chamber 8 of the pump during th two suction strokes occurringin the course of one full revolution of the plunger, the groove 9alternatingly connects the supply port 11 for the lubricating oil andthe supply port 12 for the light fuel leading into the working chamberof the plunger with the pressure chamber 8 of the pump, whereas duringthe delivery strokes following the suction strokes the groove 9 connectsthe pressure chambers 55 with one of the radial delivery galleries 13and 13a leading from the working chamber 10 of the plunger and extendingat right angles to the ports 11 and 12. The supply of the lubricatingoil and the light fuel to the ports 11 and 12 formed in the pump body iseffected through connectors 15 and 16, respectively, threaded into thepump body. The delivery galleries 13, 13a in the form of drilled holeslead to an annular mixing chamber 17 in pump body 14. The mixing chamberin turn is connected to a delivery union 19 screwed to the pump casing18 which serves to connect the delivery line to an internal combustionengine.

An adjustable suction stroke limiting member cooperating with pumpplunger 1 is provided for the purpose of controlling the amounts oflubricating oil and light fuel to be delivered during each deliverystroke of the pump plunger. This suction stroke limiting member isconstiuted by a stop pin 20 disposed coaxially with the plunger 1 andslidably mounted in pump casing 18; the axial position of the stop pinis controlled by an adjustable eccentric 21 mounted for rotation withinthe pump casing. Mounted on a shaft 22 carrying the eccentric andextending out of the pump casing 18 is an adjustingarm 23 carrying aball-headed pin 24 to which a suitable operating linkage may beconnected. A torsion spring 25 biases the adjusting arm 23 towards astop screw 26 carried by a lug projecting from the pump casing 18. Withthe adjusting arm 23 abutting the stop screw 26, the pump is adjustedfor minimum delivery. The minimum delivery of the pump can be adjustedby means of stop screw 26 which may be locked in position by means of alock nut 27.

The pump of the invention is driven at a speed which bears a constantratio to the speed of the internal combustion engine. For this purposethe end of pump drive shaft 2 projectiong from pump casing 18 is formedin such a manner that it may be connected by means of a positivelyacting coupling either to the crankshaft of the internal combustionengine or to an auxiliary drive connected to the latter. A mountingflange 28 formed on the pump casing 18 serves to secure the pump to thecasing of the internal combustion engine.

What is claimed is:

1. A valveless plunger type oil pump for lubricating internal combustionengines comprising a pump housing and a cylinder, a pump plunger Withslot means disposed in said cylinder for simultaneous reciprocating androtary movement, said cylinder and plunger forming a pressure chamber, afuel-oil mixing chamber in said cylinder having inlet passages disposedapproximately 180 apart and adapted to communicate with said slot means,oil inlet passage means disposed approximately 90 from said chamberinlet passages, fuel inlet passage means disposed approximately 90 fromsaid mixing chamber inlet passages and approximately 180 from said oilpassage means, said oil and fuel means adapted to communicate with saidslot means, means for simultaneously reciprocating and rotating saidplunger to communicate said pressure chamber and slot means first withsaid oil means, then with one of said inlet passages to deliver oil tosaid mixing chamber, then with said fuel passage means, and then withthe other inlet passage to deliver fuel thereto, and outlet means fordischarging fuel and oil from said mixing chamber, whereby said pumpprovides successive suction and successive delivery strokes.

2. The oil pump according to claim 1, wherein said mixing chamber is aring-shaped channel coaxially arranged around said plunger and connectedto said pressure chamber by said inlet passages in said cylinder.

3. The oil pump according to claim 1, wherein said plunger slot means isan axially directed slot which opens toward said pressure chamber.

4. The oil pump according to claim 1, wherein said means forreciprocating and rotating said plunger comprises a gear wheel beingengaged with a worm gear attached to a drive shaft.

5. The oil pump according to claim 4, wherein said means forreciprocating and rotating said plunger includes a return spring and acam means arranged at the lower surface of said gear wheel, said cammeans cooperating with a pin fixedly secured to said pump housing, andsaid cam means.

6. The oil pump according to claim 5, including means limitingreciprocating movement of said plunger for controlling the quantity ofsaid fuel and said oil to be delivered at each delivery stroke.

7. The oil pump according to claim 6, wherein said limiting meanscomprises a pin arranged coaxially with said plunger and axiallyslidable in said pump housing, the axial position being adjusted by theangular position of an eccentric means.

8. The oil pump according to claim 6, wherein said eccentric means isfixedly secured to a shaft rotary movable in said pump housing, saidshaft including an adjusting arm and a torsion spring biasing said armtowards an abutment arranged on said pump housing for causing said oilpump to deliver a minimum quantity.

9. The oil pump according to claim 8, with said arm further including anadjustable screw controlling the position of said abutment.

References Cited by the Examiner UNITED STATES PATENTS 4/48 Fenney 103-71/61 Meurer 1037

1. A VALVELESS PLUNGER TYPE OIL PUM FOR LUBRICATING INTERNAL COMBUSTIONENGINES COMPRISING A PUMP HOUSING AND A CYLINDER, A PUMP PLUNGER WITHSLOT MEAN DISPOSED IN SAID CYLINDER FOR SIMULTANEOUS RECIPROCATING ANDROTARY MOVEMENT, SAID CYLINDER AND PLUNGER FORMING APRESSURE CHAMBER, AFUEL-OIL MIXING CHAMBER IN SAID CYLINDER HAVING INLET PASSAGES DISPOSEDAPPROXIMATELY 180* APART AND ADAPTED TO COMMUNICATE WITH SAID SLOTMEANS, OIL INLET PASSAGE MEANS DISPOSED APPROXIMATELY 90* FROM SAIDCHAMBER INLET PASSAGES, FUEL INLET PASSAGE MEANS DISPOSED APPROXIMATELY90* FROM SAID MIXING CHAMBER INLET PASSAGES AND APPROXIMAELY 180* FROMSAID OIL PASSAGE MEANS, SAID OIL AND FUEL MEANS ADAPTED TO COMMUNICATEWITH SAID SLOT MEANS, MEANS FOR SIMULTNAEOUSLY RECIPORCATING ANDROTATING SAID PLUNGER TO COMMUNICATE SAID PRESSURE CHAMBER AND SLOTMEANS FIRST WITH SAID OIL MEANS, THEN WITH ONE OF SAID INLET PASSAGES TODELIVER OIL TO SAID MIXING CHAMBER, THEN WITH SAID FUEL PASSAGE MEANS,AND THEN WITH THE OTHER INLET PASSAGE TO DELIVER FUEL THERETO, ANDOUTLET MEANS FOR DISCHARGING FUEL AND OIL FROM SAID MIXING CHAMBER,WHEREBY SAID PUMP PROVIDES SUCCESSIVE SUCTION AND SUCCESSIVE DELIVERYSTROKES.